Observation of solvatochromism in CdSe colloidal quantum dots

We report solvatochromatic shifts in the absorption spectra of colloidal CdSe quantum dots that are consistent with the change in polarization energy of the quantum-confined exciton. Good agreement with theory is found when the screening from the ligand shell is included. The polarization energy also accounts for the spectral shift between dilute dispersions and close-packed quantum dot solids. Experiments with pure and mixed-size quantum dot solids suggest that solvatochromism dominates the redshift observed with quantum dot (2-6-nm diameter) solids.